The Organic Light Emitting Display (OLED) panel possesses many outstanding properties of self-illumination, low driving voltage, high luminescence efficiency, short response time, high clarity and contrast, near 180° view angle, wide range of working temperature, applicability of flexible display and large scale full color display. The OLED is considered as the most potential display panel.
The OLED panel can be categorized into two major types according to the driving methods, which are the Passive Matrix OLED (PMOLED) and the Active Matrix OLED (AMOLED), i.e. two types of the direct addressing and the Thin Film Transistor (TFT) matrix addressing. The AMOLED comprises pixels aligned in array, which belongs to the active display type and the illumination efficiency is high.
Before the AMOLED display panel leaves the factory after the manufacture is accomplished, it has to pass the Cell Test (CT) for detecting whether the thin film transistors of controlling the respective pixels in the AMOLED display panel normally work or not, and whether the scan lines and the data lines of transmitting signals to the respective thin film transistors are normal or not. Therefore, the panel detecting circuit is generally located outside the display region of the AMOLED display panel.
FIG. 1 is a diagram of a detecting circuit of an AMOLED display panel detecting circuit according to prior art. The AMOLED display panel detecting circuit according to prior art comprises a plurality of signal lines 100′, a plurality of signal fanout lines 200′ correspondingly coupled to the signal lines 100′, a plurality of test TFTs 310′ correspondingly coupled to the signal lines 100′, a test control line 320′ coupled to all the test TFTs 310′ and a plurality of test lines 330′. The test TFT 310′ comprises a gate, a source 312′, an active layer 313′ and a drain 314′, wherein the test control lines 320′ serve as all the gates, and the sources 312′, the drains 314′ and the signal lines 100′ are at the same layer, and one drain 314′ is correspondingly coupled to one signal line 100′, and the sources 312′ of all the test TFTs 310′ in charge of testing pixels of the same color are correspondingly coupled to one test line 330′. As the AMOLED display panel detecting circuit starts working, the test control line 320′ receives the test control signal provided by the panel test terminal and activates all the test TFTs 310′. Meanwhile, the test line 330′ receives the test signal provided by the panel test terminal, and transmits the same to the corresponding signal line 100′ through the test TFT 310′ for testing whether the panel works normally or not. As the detection is finished, the panel test terminal stops providing the test control signal and the test signal. The test control signal line 320′ receives no signal and the test TFT 310′ is deactivated. The display panel normally displays. The AMOLED display panel detecting circuit according to prior art occupies a certain layout space but merely for the detection.
At present, the defect repair of the AMOLD display panel, and particularly the line defect repair is relatively more difficult. Generally, only the bright line can be repaired to be the dark line, which will influence the quality of the AMOLED display panel. Thus, it is necessary to design the repair circuit for promoting the yield as possible. As regarding the repair circuit of the line defect of the AMOLED display panel according to prior art, the repair bus and the repair line are commonly added into the display panel. Not only more layout space is occupied but the signal of the defect signal line needs to be sent back to the control IC for control. The additional requirement exists for the control IC, which is not applicable for the line defect repair of the small size, high resolution AMOLED display panel.